South east is best and most constant. You should be looking at Cape Leeuwin for the wind reading and Margaret River for the forecast, just add 10 knots to the forecast. You will definetely need to take small kites, I was well lit on a 7m (90 kgs) sunday before last, most guys now using 6's. I saw a guy pumping up a 5m yesterday as I was leaving !
Awesome fun in the ocean and super flat water in the river ! You will be impressed !